U.S. patent application number 11/881454 was filed with the patent office on 2008-02-14 for automated level indicator for liquids container.
Invention is credited to Lucian Hite III Lyall.
Application Number | 20080036615 11/881454 |
Document ID | / |
Family ID | 46329057 |
Filed Date | 2008-02-14 |
United States Patent
Application |
20080036615 |
Kind Code |
A1 |
Lyall; Lucian Hite III |
February 14, 2008 |
Automated level indicator for liquids container
Abstract
An improved level indicator is provided as a completed
dispensing unit or as a retrofit and includes the capability for
measuring liquid level, time elapsed, temperature, two-phase
presence within the drainage pipe for very accurate level sensing,
as well as the ability to set combinational limits based upon any
of the above measured characteristics. An indicator can visually
indicate to food service workers the state of the liquid being
dispensed.
Inventors: |
Lyall; Lucian Hite III;
(Rancho Santa Margarita, CA) |
Correspondence
Address: |
Harrington & Harrington;Curtis L. Harrington
Suite 250
6300 State University Drive
Long Beach
CA
90815
US
|
Family ID: |
46329057 |
Appl. No.: |
11/881454 |
Filed: |
July 27, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10917883 |
Aug 13, 2004 |
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11881454 |
Jul 27, 2007 |
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Current U.S.
Class: |
340/614 |
Current CPC
Class: |
G01K 2207/02 20130101;
B67D 3/0093 20130101; G01F 23/18 20130101; B67D 3/0077 20130101;
B67D 3/045 20130101; G01K 13/00 20130101 |
Class at
Publication: |
340/614 |
International
Class: |
G01F 23/14 20060101
G01F023/14 |
Claims
1. An indicator system for potable liquid dispensing equipment
comprising: a liquid reservoir having a drainage pipe; a valve
connected to said drainage pipe for dispensing liquid; a display; a
processing circuit having an output connected to said display; and
a pressure output transducer having a pressure connection having a
first end connected to said pressure output transducer and a second
end to said drainage pipe at a location between said valve and said
liquid reservoir, said pressure output transducer located at a
height level of said drainage pipe, said pressure output transducer
having an outputted signal connection to said processing circuit,
said outputted signal indicative of said pressure at said drainage
pipe.
2. The indicator system as recited in claim 1 wherein said pressure
connection is a fluid conduit extending between said drainage pipe
and said pressure output transducer.
3. The indicator system as recited in claim 2 and further
comprising a two phase fluid sensor associated with said drainage
pipe and is utilized to detect the level of fluid within said
drainage pipe.
4. The indicator system as recited in claim 2 wherein said pressure
connection fluid conduit extending between said drainage pipe and
said pressure output transducer extends upwardly from said drainage
pipe and back down to said a pressure output transducer at the
level of said drainage pipe.
5. The indicator system as recited in claim 1 and further
comprising a temperature sensor connected to said processing
circuit for measuring at least one of the temperature of fluid in
said reservoir and the temperature of fluid in said drainage
pipe.
6. The indicator system as recited in claim 5 wherein said
temperature sensor is associated with said drainage pipe to measure
a temperature of said liquid in said drainage pipe.
7. The indicator system as recited in claim 5 wherein said
temperature sensor is associated with said liquid reservoir to
measure a temperature of said liquid in said reservoir.
8. The indicator system as recited in claim 5 and wherein said
display indicates a passage of time since said reservoir was last
refilled.
9. The indicator system as recited in claim 8 and wherein said
display re-sets said indication of passage of time whenever said
pressure at said drainage pipe drops below and then rises above a
pressure indicating that said reservoir is filled to a threshold
percent of reservoir filled level.
10. The indicator system as recited in claim 9 and wherein said
threshold percent of reservoir filled level is about twenty
percent.
11. The indicator system as recited in claim 1 and further
comprising a two phase fluid sensor associated with said drainage
pipe and said sensor processing circuit to detect at least a
partial absence of liquid within said drainage pipe by detecting
the presence of a liquid phase and a gas phase within said drainage
pipe.
12. The indicator system as recited in claim 1 and wherein said
processing circuit records the passage of time, and wherein said
display gives a visual indication of said passage of time.
12. The indicator system as recited in claim 10 and wherein said
display indicates a combined limit threshold failure based upon a
combination of said temporal limit threshold failure and said level
of liquid within said liquid reservoir according to a pre-set time
and liquid level combination.
13. The indicator system as recited in claim 1 and further
comprising a temperature sensor associated with said pressure
output transducer and connected to said processing circuit.
14. The indicator system as recited in claim 1 and wherein said
pressure output transducer measures the pressure at said drainage
pipe relative to ambient pressure.
15. The indicator system as recited in claim 16 wherein said
drainage pipe further includes an upwardly extending branch and
further comprising a fitting for providing, with said upwardly
extending branch, a first expanded cross sectional area relative to
a second cross sectional area of said pressure connection between
said pressure output transducer and said drainage pipe.
16. The indicator system as recited in claim 1 wherein said
drainage pipe, said valve, said housing, said display, said
processing circuit and said pressure output connection from said
drainage pipe is integrated into a single unit.
17. A retrofit indicator system for use with potable liquid
dispensing equipment having a liquid reservoir and drainage pipe
and comprising: a shank for forming a part of said drainage pipe of
said liquid reservoir and having a valve for dispensing liquid; a
display; a processing circuit having an output connected to said
display; and a pressure output transducer having a pressure
connection having a first end connected to said pressure output
transducer and a second end to said drainage pipe at a location
between said valve and said liquid reservoir, said pressure output
transducer located at a height level of said drainage pipe, said
pressure output transducer having an outputted signal connection to
said processing circuit, said outputted signal indicative of said
pressure at said drainage pipe.
Description
[0001] This application is a continuation-in-part application of
co-pending U.S. Pat. No. 10/917,883 filed Aug. 13, 2004.
FIELD OF THE INVENTION
[0002] The present invention relates to the field of liquid level
sensing, and more particularly to liquid level sensing for non
hazardous, non-corrosive materials, and specifically to level
indicators used in food service equipment.
BACKGROUND OF THE INVENTION
[0003] The standard for level indication equipment has for years
been the sight glass. Sight glasses are visible channels, typically
tubes, which share part of the volumetric capacity of a vessel and
which occupy a level in the visible channel the same as the liquid
inside the main vessel. Sight glasses have always had operating
limitations that the fittings securing the glass must not leak,
that the fittings and glass should be able to be secured tightly
enough to withstand the pressure inside the vessel.
[0004] Food service vessels typically utilize large round sight
glasses having a lower end connected to open into the bottom and an
upper end connected into the top of a main liquid reservoir. The
liquid level in the sight glass will match the level in the
reservoir as gravity pulls on both liquid columns the same. It is
not often realized the rough treatment that such vessels undergo
during a typical day of usage. Workers are often not strong enough
to supply the strength and acumen necessary to treat a heavy vessel
with adequate care. A broken sight glass can result in spillage of
contents on carpeting, often creating a coffee stain requiring
specialized cleanup. Breakage of sight glasses also poses a danger
to nearby occupants. Further, a rising number of incidents have
been observed where the glass tubes may be intentionally broken by
workers to obtain it for recreational drug use. Sight glasses
cannot effectively be protected by the use of cages and screens as
they would drive up the equipment and maintenance cost
significantly, as well as to obscure the visual determination of
liquid level. Cleaning and replacement would also then be a problem
as any protector would require specialized cleaning and likely
removal as a pre-requisite to replacement.
[0005] Having to provide site glasses along the whole effective
height of the reservoir also blocks the ability to further utilize
other components with it. Insulation blankets cannot be used
efficiently where they are so oversized that they cover over the
sight glass and create unrestricted air pockets, while a close
fitting insulation blanket cannot fit over the sight glass. Other
components which are inhibited by the interruption of an even
radial surface include protective sleeves, decorative sleeves,
advertising, handling instructions and more.
[0006] Another problem with sight glasses is that they must
typically be large to insure that enough liquid is swept through
them to prevent any collection of debris which might block the
sight glass tube. As such, smaller tubes or small flat plastic
channels do not work well. Anything smaller than a large glass tube
would likely be able to collect debris and to malfunction.
[0007] Sight indicators are important so that food service can be
supplied efficiently and accurately. When food and drink reservoirs
go empty, users are inconvenienced and sales are lost. When food
workers change out half empty containers for filled ones to prevent
outages, unused food product is lost. Likewise, hot or cold food
and drink which has become room temperature will continue to
inconvenience users and result in lost sales. A half reservoir of
cold coffee will not be consumed despite a room full of people
thirsty for coffee. In terms of overall economics, food service is
primarily a service, and when service suffers, sales will suffer.
Accommodation must be made to at least enable high level service
providers to provide the high level of service when desired.
[0008] U.S. Pat. No. 7,000,468 issued on Feb. 21, 2006 to Doorhy et
al, and incorporated by reference herein gives one example of a
system using a series of vertical connections leading to a board
mounted pressure sensor. The problems are several. First, there are
a series of pressure fittings which multiply the ability to leak.
Secondly, a column is established which has the ability to
introduce error, as well as to clog. Because of the relatively
large diameter column established, any inversion during cleaning
can fill the established column and cause clogging of the so-called
"check" valve device (which is not as much a check valve to permit
flow in one direction as it is a filter.
SUMMARY OF THE INVENTION
[0009] An improved level indicator takes advantage of the universal
visual impression of typical sight glasses, but without the
disadvantages of a physical sight glass protruding from the main
body of the reservoir. An improved level indicator takes advantage
of the universal visual impression of typical sight glasses, but
without the disadvantages of a physical sight glass protruding from
the main body of the reservoir. In addition, other quantities are
measured, including two-phase presence in a drainage pipe,
temperature of the liquid product measured against either the drain
pipe or reservoir, and temporal passage. Each of the measured
quantities can result in an individual visual indication, or can
thresholded combinationally to provide a combined threshold limit
for initiating visual indication.
[0010] A sealed unit is provided low on a food dispensing reservoir
and upstream of a dispensing valve with a sensor in fluid
communication with the static pressure in the dispensing valve.
Because the sealed unit is in communication with the liquid in the
reservoir at the lower position only, several alternatives may be
utilized to equate the static pressure with the liquid level in the
food service container reservoir.
[0011] First, an independent ambient pressure sensor may-be
utilized. This will enable the unit to distinguish between the
exact levels of fullness in Denver, Colo. at a mile high altitude
versus Long Beach, Calif. at sea level. Second, a calibration
routine may be performed on startup where the sensor recognizes a
change in pressure equivalent to a transition from empty to
full.
[0012] For example, where a reservoir, for example is filled to a
height of one foot, and where water is used, the change in static
pressure will be from ambient air pressure to the addition of
62.427 pounds per square foot, or 0.43 pounds per square inch
(PSI). At a given temperature at sea level, the pressure is 14.696
PSI. At the same temperature one mile above sea level, the pressure
may be 12.096 PSI. Yet the range over which the sensor must measure
is 0.43 PSI for a one foot water column height. Higher or shorter
main reservoirs 31 should have proportionately more or less
resolution. In most commercial coffee containers of the type
pictured in FIG. 1, a pressure measuring ability range of from
about 0-28'' water column resolution is sufficient. Thus, the
sensor may be programmed to measure a rapid change in pressure and
to take the rapid change on fill up, rather than a measure of an a
scalar absolute pressure. Thus, it will measure and give an
indication of level based upon the rapid 0.43 PSI difference as its
working range between an indication of full and empty.
[0013] Third, it may combine pressure sensing of the ambient air
pressure in addition to sensing a pressure change on fill-up.
Fourth, the sensor may store and record an average set of maximum
and minimum pressure values over time to give a time average
pressure range as a time average maximum pressure and a time
average minimum pressure.
[0014] The sensor of the invention will also have a range of other
sensing and service-out indicators. First, the sensor may include
an optional "air gap" optic sensor which can be utilized in
conjunction with its small elastomeric pressure tube or with a
separate sealed fiber optic tube. A light pulse sent into the
product tap pipe will reflectively return if the liquid level in
the tap pipe is low enough to create a partially filled channel. A
light impulse will be returned to the sensor if the liquid level in
the tap pipe is not full, representative of the last eighth of an
inch range of liquid flow. This can be used to trigger a special
flashing alarm to insure that the food service workers recognize it
instantly.
[0015] In addition, other indicators can be employed using the same
sensor area just upstream of the drain pipe, as well as contact of
the sensor with the main reservoir, including temperature. Minimum
acceptable temperature of the product can be programmed. In the
alternative, the sensor can be programmed to sense the initial
temperature of the reservoir and to give a food service indication
when it has changed to a temperature within, say 20.degree.
Fahrenheit of room temperature. Coffee, for example would begin at
about 190.degree. Fahrenheit, and when the temperature drops to say
110.degree. Fahrenheit, an temperature indicator would light.
Likewise, iced tea would begin at about 37.degree. Fahrenheit and
would give a temperature problem indication at about 60.degree.
Fahrenheit.
[0016] For even more closely managed liquid food service
dispensing, a time indicator could also be used. The sensor may
trigger automatically on fill by either a temperature trigger, hot
or cold, or by a fill pressure trigger. The timer may be set to one
time difference for initial introduction of a cold liquid and to a
second time difference for initial introduction of a hot liquid, or
the time may be programmed. Time indications can be important where
the sensor of the invention is used with a heated vessel, and where
product spoilage or lack of freshness is keyed more to passage of
time than to temperature or usage rate.
[0017] In a further embodiment, the provision of an extended
pressure conduit along with co-location of the sensor at the
centerline of the exit shank can significantly reduce error.
Further, the use of a fitting which is larger than the pressure
conduit can help reduce any inadvertent errors by the ratio of the
cross sectional surface area of the fitting divided by the cross
sectional surface area of the fitting. The error reduction is
particularly reduced over the first bit of pressure drop and before
the liquid reaches the pressure conduit.
[0018] The compact version of a housing and spigot assembly is
advantageous for use where a connection can be made at part of an
existing exit shank, whether through fitted connection or via
cutting and gluing. In some cases, a retrofit replacement can be
had by leaving an existing shank and exit valve in place and
tapping into the existing tank to form an upwardly extending branch
over which a fitting can be sealably engaged.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The invention, its configuration, construction, and
operation will be best further described in the following detailed
description, taken in conjunction with the accompanying drawings in
which:.
[0020] FIG. 1 is a perspective view of a food service liquid
dispenser having a reservoir mounted above an integral stand and
having a front tap and protector with the sensor of the present
invention shown exploded from it;
[0021] FIG. 2 is a side sectional view taken along line 2-2 of FIG.
1 and illustrating the connection to the valve and drain pipe, with
the pressure tap being above the drain pipe;
[0022] FIG. 3 is a closeup view of one embodiment of the display
area seen in FIG. 1;
[0023] FIG. 4 is a closeup view of a housing and pipe connection,
compact and advantageous for either retrofit or original
installation; and
[0024] FIG. 5 is a rear view of the housing and pipe connection
seen in FIG. 4.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0025] The process and apparatus described herein will in
concentrate on the somewhat schematic use of a sensor in
conjunction with the drain pipe of a liquid food service container
upstream of the valve. Referring to FIG. 1, a generic arrangement
for a food service liquid dispensing container 11 is shown as
having an integrated base stand 13 which supports a vessel 15
above.
[0026] The base has a main "U" shaped support 21 to provide easy
clearance for the entry of drinking cups and user access. From the
main "U" shaped support 21, a series of vertical columns 23 attach
to a base support 25.
[0027] A main reservoir 31 has a lid 33 with a small vent hole 35.
An optional bail handle 37 is shaped to accommodate the lid 33 and
folds away to enable access to the lid 33. An upper fitting 39
provides some interruption of the main cylindrical surface of the
reservoir 31. A cylindrical surface 41 is generally only
interrupted by a tap 43. Tap 43 in the alternative, could have
emerged from beneath the main cylindrical surface 41, such as from
a point underneath the cylindrical surface 41. The arrangement of
the tap can further free the lower areas of the cylindrical surface
41.
[0028] Tap 43 may have a flange fitting 45 as an expanded area of
material acting a washer to spread its bearing surface onto an
expanded area of cylindrical surface 41, especially where it has an
insertion portion extending into the inner reservoir (not shown in
FIG. 1) and secured with axial force. The tap 43 being shown is
non-integrated into the remainder of the inventive sensor and
indicator for familiarity and to demonstrate that the sensor and
indicator can be supplied to work with existing components, or it
can be supplied along with a tap 43 assembly.
[0029] Tap 43 includes a main horizontally disposed faucet shank,
or drainage pipe 47 upstream of a vertical drain 49. Drain pipes
need not be horizontal and may be vertical, but the configuration
of FIG. 1 simply happens to have a horizontal pipe 49. A vertical
pipe below a main reservoir would give a maximum vertical pressure
head and would be more accurate in determining the pressure
throughout a fuller height of fluid head than a horizontal tap, and
particularly a tap 43 which is above the lowermost extent of a
liquid level in a reservoir 31. Continuing away from the
cylindrical portion 41, the horizontally disposed drainage pipe 47
includes a fitting 51 supporting an operating handle 53. A thin
conduit 55 extends from the horizontally disposed drainage pipe 47
from a position upstream of the operation of the valve components
within the tap 43, such that the thin conduit 55 is in fluid
communication with the liquid within the main reservoir 31. Thus,
the pressure may drop temporarily when the handle 53 is activated
to allow liquid to flow through the vertical drain 49, but when the
tap is shut, the static pressure head upstream of the valve opening
will be transmittable along the conduit 55.
[0030] Further, the orientation and size of conduit 55 can prevent
contact of the server media liquid with the transducer. The liquid
will compress any air present in the conduit 55 tubing to form a
meniscus which will not wet the walls of the conduit 55 beyond the
liquid/air interface. This liquid-gas dividing line may move back
and forth along the length of the conduit as varying pressure is
exerted on the transducer due to changes of liquid level in the
reservoir. This will allow the air-liquid interface to move, to
compress the air bubble against any transducer to which it is
connected, yet isolate the actual transducer from liquid contact.
This "air bubble isolation" is assists the long term performance
and accuracy of the transducer. This method provides for a pressure
reading without a hot or cold media directly contacting the
transducer die. Potting, or encasement of all components
surrounding the end of the conduit 55 will further prevent leakage
and contribute to the operation of this principle.
[0031] To the right and displaced from the tap 43 is an sensor
housing 61 having a display area 63. Display area 63 may utilize
LED's or liquid a liquid crystal display. Sensor housing 61 has a
lower inverted "U" shape to help integrate the fit over the main
horizontally disposed drainage pipe 47. Where the sensor housing 61
is rigidly attached directly to the main horizontally disposed
drainage pipe 47, the space between the cylindrical surface 31 and
the rear of the sensor housing 61 will be available for adding
placards, insulating layers, or other flat materials, including
signage.
[0032] The end of thin line 55 is shown free, but will be connected
to the rear of the sensor housing 61, possibly into a potted
volume. The additional length of thin line 55 could be provided to
enable removal of the sensor housing 61, especially where removal
is necessary to change a battery. In the alternative, a side
battery door 65 may be provided. Further, a photo voltaic array 67
may be provided to power the electronic components within the
housing 61 either alone or as a supplement to a battery located
behind the battery door.
[0033] Referring to FIG. 2, a sectional view taken along line 2-2
of FIG. 1, but with the sensor housing 61 in place, reveals further
details of the components assembled into an indicator system 71.
Again, the indicator system 71 can be packaged with or without the
associated assembly of the tap 43. From the left, an internal
reservoir 73 contains a liquid 75 shown by periodic interrupted
horizontal lines. In this instance, the flange fitting 45 can be
seen to include a two sided structure with a matching internal
flange portion embracing the effective main reservoir wall 77. The
wall 77 can be made of layers of material which may include a
sleeve, applied layers, or insulation layers.
[0034] Liquid 75 is seen to freely exist within the flange fitting
45 and the short length of main horizontally disposed drainage pipe
47 extending beyond the flange fitting 45. A valve sealing member
81 forms a pressure seal into an internal portion of the main
horizontally disposed drainage pipe 47, just before the vertical
drain 49 is accessed. In the tap 43, fitting 51 houses spring
biased (spring mechanism not seen to maintain clarity of the
drawing) valve sealing member 81 which is constantly biased to
enter the end of the main horizontally disposed drainage pipe 47 to
shut off the liquid flow.
[0035] Handle 53 is seen to attached to pivot with respect to valve
sealing member 81 and any pivoting of handle 53 will cause the
valve sealing member 81 to be withdrawn from sealing contact with
the inside of the main horizontally disposed drainage pipe 47 to
allow liquid to flow into the vertical drain 49.
[0036] In normal usage, the tap 43 and its assemblage will remain
closed the vast majority of the time. Thus, the thin line 55 will
be enabled to register the pressure at the main horizontally
disposed drainage pipe 47, and into a circuit board 85 sensor
processing circuit 87. Sensor processing circuit 87 may be a
microprocessor having digital and or analog component circuitry and
whose main function is to receive sensor signals and to interpret
the sensor signals utilizing an instruction set and to send
appropriate information to components in the display area 63, so
that necessary states and indications of necessary actions to be
taken can be displayed.
[0037] The location of the end of the thin line 55 should be as low
as possible with regard to a bottom floor 89 of the internal
reservoir 73 as is possible, so that positive pressure will be
present throughout the complete range of liquid 75 level within the
internal reservoir 73 as is possible. In an integrated indicator
system 71, the sensor electronics may be located immediately
adjacent the main horizontally disposed drainage pipe 47,
preferably below or to the side.
[0038] Also seen within the sensor housing 61 is a battery 91 held
between a pair of battery contacts 93. The battery 91 may be
connected to the photocell 67 (connection is not shown) to
supplement its power or to recharge it, or to allow battery 91 to
act as backup power in dimly lit conditions. A potting line 95 is
seen to illustrate that all of the components of the indicator
system 71 can be potted, and or formed integrally with the tap 43
which will eliminate the need for fittings, eliminate the
possibility of disconnection of the thin line 55, and eliminate any
possibility of external leakage. Only the battery 91 and its
battery contacts 93 need be outside the potted area. Further, the
circuit board 85 and sensor processing circuit 87 may also be made
to be located close to the main horizontally disposed drainage pipe
47 to further reduce the size of the indicator system 71.
[0039] In terms of temperature, an additional blind bore 101 could
be provided in the main horizontally disposed drainage pipe 47 with
a temperature sensor 103, such as a thermocouple connected by a
wire set 105 to the circuit board 85 sensor processing circuit 87.
As another example, a thermal sensor 111 can be mounted directly
adjacent the main reservoir wall, and connected by a wire set 113
to the circuit board 85 sensor processing circuit 87. The accuracy
of either locating a temperature sensor adjacent the main reservoir
31 or within the main horizontally disposed drainage pipe 47 will
depend upon the materials of each of these structures, the degree
of insulation and more.
[0040] Further, the thin line 55 can be made of an optical
material. In this instance, the sensor processing circuit 87 can
periodically generate a light pulse into the thin line 55. The end
of the thin line 55 which terminates at the top of the main
horizontally disposed drainage pipe 47 will generate a reflection
if the liquid 75 has an air space over it within the main
horizontally disposed drainage pipe 47, to indicate a level
approaching a terminally low liquid level. In the alternative, a
single, solid fiber optic line 117 can be provided directly into
the main horizontally disposed drainage pipe 47 and terminating
even with the internal wall of the main horizontally disposed
drainage pipe 47 and perhaps polished even with the internal
wall.
[0041] Fiber optics can easily work within the main horizontally
disposed drainage pipe 47 to essentially detect two phase fluid. It
is clear that a pipe, especially a vertical conduit cannot sense
two phase pressure where the liquid level must rise vertically, to
some degree above the pipe. Two phase pressure within a pipe line
can only be measured by some device which can compute the level of
fluid within a pipe. Pressure can be measured if a bottom tap from
a pipe were made, but this is practically unworkable, unsanitary
and unsafe. A bottom tap from a pipe would always leave old product
in a loop extending from the bottom of the pipe to a pressure head
conduit. Where the pressure is measured in a terminal pressure
connection at the other end of a "U" tube, the product in the tube
will always be present and will never be cleared. In this
configuration, mold, germs, bacteria and mildew will be encouraged
to grow within the pressure determining apparatus and can cause
harm or in the alternative will create the need to completely
disassemble the pressure measuring apparatus.
[0042] As a result, the measurement of two phase flow from a
pressure apparatus which takes its pressure signal from the bottom
of a pipe is inherently problematic. In one embodiment of a two
phase measuring apparatus, light introduced into a filled tube will
reflect only or predominantly at the junction of the fiber and its
refractive index, as it passes into the fluid and its refractive
index. An additional reflective junction will be present at the
surface of the liquid 75 when air is present in pipe 47. A much
greater reflection will occur at the end of the fiber when the tube
47 is partially filled, and a further reflection will occur at the
junction of the air and liquid 75 interface within the tube 47.
Thus, any gravitationally induced volume of air in the tube 47 will
register a significant reflection in any fiber optic transmission
structure regardless of whether it is thin line 55 or solid fiber
optic line 117.
[0043] A similar arrangement could be used where a drainage pipe is
vertical, but where a more sensitive change in refractive index is
used, or where some mode of reflection or absorption of light
against the opposite pipe wall is utilized. A horizontal drainage
pipe would function much more efficiently in an indication of
complete outage, as there is no level in the main reservoir 31 to
hold liquid 75 below such a bottom mounted tap. In this instance, a
flashing "out of product" indicator would save users from the
temptation to try the operating handle 53 in vain. In the case of
the horizontal pipe 47, and depending upon the depth of the main
reservoir 31 below the pope 47, users might be able or tempted to
tilt the container 11 forward to obtain the last bit of liquid 75.
The indications in the display area 63 can discourage this by
showing "empty" and possibly help reduce mishaps from attempts at
tilting the container 11. Thus, the indicator system 71 can
decrease the incidences of tampering by non-authorized personnel
and reduce mishaps.
[0044] In yet another alternative, a pressure cell 121 can be
mounted inside the main horizontally disposed drainage pipe 47,
with a transmission wire set 123 leading back to the sensor
processing circuit 87. An internally mounted pressure cell 121
would preferably be self contained, with a surface exposed which is
not in the way of flow, and which is somewhat remote from
experiencing force. Pressure cell 121 is shown on the bottom of
main horizontally disposed drainage pipe 47 but could be located
anywhere about its circumference, or indeed anywhere in as close of
a proximity as practicable in contact with the lower most liquid 75
to gather the static head pressure efficiently.
[0045] Referring to FIG. 3, a closeup view of one embodiment of the
display area 63 is seen. A central upper area includes a vertical
stack of horizontal bars 131 which individually illuminate to
reflect the liquid 75 level within the main reservoir 31. It is
important to have an indicator which can be instantly interpreted
by workers of all languages, and this is the case for display area
63. Vertical stack of horizontal bars 131 may preferably be green
in color and indicate either the complete range of fill, or may
indicate the top 80% of fill to indicate to food service workers
that the level may be getting low, but should be watched.
[0046] Below the vertical stack of horizontal bars 131 is a second
area of diminishing shapes 133. The shapes 133 may be red in color
and indicate a series of levels within the last 20% of the range of
the liquid 75 level within the main reservoir 31. To the left side
of the display area 63 is a first hourglass shaped stack of
horizontal bars 135. The upper set of bars 135 may be green and the
lower one or two may be red. As a timer, the bars 133 can indicate
the progression of time during which the liquid 75 has been present
within the main reservoir 31.
[0047] A second hourglass shaped stack of horizontal bars 137 is
located to the right, and may flash red at different rates to
indicate an emergent need to replace the liquid 75. Where the
sensor processing circuit 87 is programmed to cumulate a growing
need for replacement of the liquid 75, the triggering of a second
hourglass shaped stack of horizontal bars 137 might occur not based
upon just one extreme, such as the falling level of liquid 75
within the main horizontally disposed drainage pipe 47 to the
extent that there is an air gap, but perhaps earlier based upon a
combination of time and low liquid level.
[0048] For example, second hourglass shaped stack of horizontal
bars 137 might trigger a flashing change indication where the
temperature was only 80% of the acceptable fall in temperature and
where the passage of time was 80% of the critical time passage.
This combinational decision to render an change product alarm which
is more sensitive than either of the two scalar progressions might
also result in a different flashing rate.
[0049] Where the flash rate is proportional to the extremity of
measured liquid 75 level and temperature circumstances, food
service workers could be instructed to replace the liquid 75 at the
slowest rate of flash (quickest circumstances) or to wait until the
most rapid rate of flash (for slowest terminal circumstances) told
to replace the product at a lesser be adjustable based upon
business dictates. For example, in a hotel where a buyer has
purchased only a single container of liquid 75, workers would know
to remove the liquid dispensing container 11 at the highest rate of
flash. Conversely, where a customer demands only the freshest,
hottest product over a given time period, food workers would be
alerted to replace the product early in the dispensation cycle,
without waiting for outages. This causes a proper increase in sales
based upon the quality level demanded. Where high quality product
is demanded, the failure in supplying it is a failure in service.
As a result, the indicator system 71 helps prevent inadequate
service.
[0050] The level of visual indication to the food service worker
can be modulated by colors, flashing, increased brightness or other
indication. Further, sensor processing circuit 87 may include an on
board electromagnetic communications capability to send a signal
back to a central station. The signal can include each of the
individually measured parameters of time, temperature, level and
two-phase bottomed out depletion, or the logic for sending a signal
based upon a combinational threshold based upon any number and
degree of the time, temperature, level and two-phase bottomed out
depletion can be formulated by the sensor processing circuit
87.
[0051] In such a system in a convention center, for example, a
central computer would be receiving signals from a series of food
service liquid dispensing containers 11, typically coffee pots, in
the center's facility. Where certain customers only purchased a
single pot, signals from the container 11 would not result in a
response. Where another customer had request a high level of
service, the computer would detect by radio, a threshold condition
and might immediately notify the food service worker by hand-held
radio, or by a pager system directing the worker to replace the
container 11 immediately.
[0052] Further, in rooms which are busy, and which are of such high
priority to have a worker assigned to be present during the event,
the central system could be disabled as to that room, relying
instead upon a much more immediate visual detection and a much
quicker replacement of food product than would be obtainable with
distributed information management and control through a computer
and paging system.
[0053] It is preferable for all of the components seen in FIG. 2,
with the exception of the main reservoir to be supplied as an
integral unit. In the construction of original equipment, assembly
time will be significantly reduced by having to merely perform the
simple step of inserting the tap 43 and attached sensor housing 61
assembly into the main reservior 31 and forming a fluid tight
connection. In terms of retrofit, the provision of a tap 43 and
attached sensor housing 61 assembly with the double flange fitting
45 replaced by a unit with a large threaded continuation of fitting
45 and a large nut for engagement of the threaded continuation,
would facilitate change out of conventional taps 43 with complete
tap and sensor sets in a manner so simple as to enable ordinary
user to make the change out.
[0054] In terms of power management, when the reservoir is empty or
has not undergone a change in some time, the display 63 and sensor
processing circuit 87 may be programmed to attain a
sleep/non-functioning mode, to save battery 91 energy. As the
sensor processing circuit 87 detects that the main reservoir 31 has
started to become filled and a pressure increase is sensed, the
sensor processing circuit 87 will wake up and start to display.
[0055] The sampling rate for the sensor processing circuit 87 may
be from 1-30 seconds. This will preclude the display from "jumping"
as the server is being filled, and will further save energy. Once
the sensor processing circuit 87 detects that a level is stable or
not increasing for a period of about two minutes or greater it will
start recording time as an indication of product freshness. A
center portion or gray bar of the timer indicator in the display
area 63 may start flashing to indicate that timing is started. Each
horizontal line may be a time increment, such as a 15 minute
increment where it is desired that food service workers are able to
monitor the temporal progress.
[0056] Once a desired time increment is timed out the upper bar
will be empty and the lower one will remain solid. This "hour glass
effect" provides and intuitive time display for product freshness
in the server. There may be 1-4 timers displayed. As each full
timer is times out, about one hour, the next timer will appear on
the display. When the server is empty and the transducer senses it
will shut off the timers and not display any horizontal bars in the
display area 63.
[0057] If the liquid dispensing container 11 is being pre-heated by
filling with liquid (such as to pre-heat with a hot liquid or
pre-chill with a cold liquid) and then dumped out it may
inadvertently start the level and timer. However once the pre
heating or cooling liquid is dumped, and where the sensor
processing circuit 87 is so programmed, the liquid dispensing
container 11 will reset to zero and wait to start again on another
fill cycle.
[0058] In a further embodiment of an even more accurate and even
more easily readable system, a more compact and unitary assembly
can be provided to give the most fundamental and easy to read
indication system which serves an advantage of facilitating
retrofit and in requiring the minimum time to train food service
workers and in giving the most accurate level readout at low
volumes.
[0059] Referring to FIG. 4, a housing and spigot assembly 201 is
seen. The housing and spigot assembly 201 has a housing 203 having
an opening 205 as a window on a display 207 which may be a liquid
crystal display. Display 207 may preferably have a number of
features, and in particular two predominant features shown in FIG.
4, including a level feature seen as a set of upper radial arced
segments 209 which indicate liquid level in a configuration which
mimics operation of a speedometer or needle gauge. In one
configuration, the arced segments 209 are divided in to six
segments, with the left most segment being an "empty" indicator,
and with the five arced segments 209 on the right indicating, for
example, increments of 20% of full volume.
[0060] With this configuration, full illumination (or blackening in
the case of a liquid crystal display) would indicate a full main
reservoir 31. As the hot or cold liquid is dispensed, to a point of
80% full, the right most arced segment 209 goes off. As subsequent
liquid is dispensed, the fifth, fourth third and second segments go
off when the liquid level falls below 60%, 40% and 20%. The
leftmost segment may be reserved for a lowest limit and may flash
when the main reservoir 31 reaches the lowermost limit. Such
flashing may assist in notifying food service workers.
[0061] On the display 207 below the arced segments 209 are a series
of ordered rectangular segments 211. There are four rows of four
segments 211 stacked in each row 211. In this one example, a four
hour time period can be divided evenly into sixteen fifteen minute
segments. The first row can represent the first hour, the second
row can represent the second hour, the third row the third hour and
the fourth row the fourth and final hour. When the filling of the
main reservoir 31 is sensed, all of the segments 211 may be
illuminated. The sensing of filling can be upon sensing of the
liquid level rising from essentially zero level to over 20% of the
main reservoir 31 level. Once filling is sensed, all of the
segments 211 may be illuminated and thereafter start a count down.
After fifteen minutes the uppermost right segment 211 may be turned
off. After another fifteen minutes, the uppermost third segment 211
may be turned off. This continues over four hours when the left
most bottom most segment 211 can be programed to shut off or to
flash. With the configuration described, the food service attendant
can be summoned with a flashing indicator, either as a flashing
leftmost arced segment 209 upon the withdrawal of the last of the
liquid from the main reservoir 31 or upon the elapsing of the last
time period and flashing of the last segment 211. The indication to
the food service worker can be a single flashing segment 209 or 211
or all of the segments 209 and 211 can be made to flash to make a
more immediate visual indication. Further, the flashing can be
augmented by other alarms, including an audible alarm, or a radio
alarm communicating with the main food service facility or possibly
an infrared transmitter transmitting to an infrared pickup in a
serving room. The housing and spigot assembly 201 or the sensor
housing 61 can provide the last link in a centralized monitoring
system for food service.
[0062] As can be seen from FIG. 4, the housing 203 is seen to
straddle the faucet shank (seen in phantom dashed line format) 215.
The faucet shank 215 can be provided as an integral part of the
housing and spigot assembly 201. In terms of providing a retrofit,
the shank 215 rear side can have a fitting for engaging an existing
drainage pipe 47, with or without cutting. For example, where a
housing and spigot assembly 201 is provided as a retrofit to a
liquid dispensing container 11 where the old spigot and valve can
be removed by disconnecting a pre-existing fitting, a similar
pre-existing fitting can be provided on the shank 215. Where the
retrofit to a liquid dispensing container 11 where the old spigot
and valve is continuous with the main reservoir 31 cannot be
removed by disconnecting a pre-existing fitting, removal may be had
by sawing or heat cutting. Techniques similar to those used for
polyvinyl chloride piping (PVC) can be used to complete the
retrofit. Other structures can be employed, such as over fitting
sleeves, conical members, and other facilitative structures, as
well as adhesives, glues and melting agents to complete a retrofit
exchange of the housing and spigot assembly 201 for a conventional
valve and spigot assembly.
[0063] In other instances, as will be shown in further detail, the
housing 203 could be provided for use over existing conventional
shanks if sufficient distance is provided between the main
reservoir 31 and the conventional valve and its operating
structures. In this case, some hole and fitting would have to be
provided in the conventional shank in order to interfit and mount
the housing 203 onto a conventional shank.
[0064] FIG. 4 illustrates the instance where a shank 215 is
provided with the housing and spigot assembly 201, and which
includes a valve 217 having an operating handle 53. Operating
handle 53 operates a vertical member 219 to provide an exit from
the shank 215 to a lower drain 49. This valve 217 operates by
angular displacement of the operating handle 53 to pull a vertical
plug to enable fluid to pass through the lower drain 49.
[0065] Referring to FIG. 5, a reverse view illustrates the
components within the housing and spigot assembly 201. Near the top
of the housing and spigot assembly 201, a circuit board 225 is seen
slightly above a battery support 227 which supports two batteries
229. Batteries 229 may preferably be two or more "AA" sized
batteries which can fit within an expected depth of the housing
203. The batteries 229 are connected to the circuit board via
connectors (not shown). The circuit board 225 is also connected to
a conductor set 231 which may include one, two or more conductors,
fiber optics, or other information conduit connecting a pressure
sensor/transducer 233 to the circuit board 225. Preferably
conductor set 231 will provide enough conductors or capacity to
both power and derive pressure data from the pressure
sensor/transducer 233.
[0066] Pressure sensor/transducer 233 is preferably a computer chip
or semiconductor having the ability to detect pressure at its
location. The pressure is made available to the location of the
pressure sensor/transducer 233 via a conduit 237 which is shown
extending over a circuitous path possibly having non blocking
kinks, loops and other extended length features. The serpentine
nature is abbreviated for drafting clarity, but an actual conduit
237 should be about 2-6 times longer, and compacted within the
applicable space in the housing 203 like optionally tied
intestines. A longer, more serpentine conduit 237 can help make the
pressure more instantly available to the pressure sensor/transducer
233 without having to provide fritted inserts, filters and the like
to help isolate the pressure sensor/transducer 233 from any
inadvertent contact with liquid 75. Since only static pressure is
being measured, the pressure drop in the serpentine conduit 237 is
negligible.
[0067] Moreover, note that pressure sensor/transducer 233 is
located adjacent the centerline of the shank 215. It is preferable
for the pressure sensor/transducer 233 to be located at a level
between the top of the shank 215 and the bottom of the shank 215,
but it is most preferable for the pressure sensor/transducer 233 to
be located at the shank centerline. This enables the ambient
pressure reference to be taken with respect to ambient air pressure
at the lowest "effective" reservoir level. Location of the ambient
pressure transducer high up can invite a significant column of
liquid 75. Further, whenever the main reservoir 31 is drained, it
is insured that there will be a much lesser chance that liquid 75
will be trapped.
[0068] An example of the error which is introduced when the sensor
is raised above the reference point is as follows. If a sensor is
mounted higher, there will be an effective vertical tube of air
between a sensor and shank 215. As a further example, what if the
pressure doubled in a twelve inch air column? Ideally, the air
present in the column would be compressed into half the volume to
indicate a doubling of the pressure. However, the material which is
pushing the gas upwardly is not other gas of the same weight and
density, but a liquid. In a weightless environment, the liquid
would be forced up to the height of half of the twelve inch column
so that the pressure would indicate a doubling. However, the column
of water which would otherwise rise six inches has weight and
gravity acts to pull it down. A six inch column of water, at about
62.4 pounds per square foot has a weight of about 0.43 pounds per
square inch or about 0.21 pounds per square inch for a six inch
column. Where a doubling of the atmospheric pressure occurred, the
error in the column would be about 0.21 pounds per square inch out
of the 14.596 pounds per square inch which would be a proper
reading. This amounts to an error of a little less than 1.5%
[0069] However, when it is considered that a beverage reservoir
operates over a range of from 1 atmosphere when empty to 1
atmosphere and say a twelve inch column when full, the error rate
is more significant. In a static, closed, sealed twelve inch
column, the addition of 0.43 pounds per square inch (resulting from
a full reservoir) causes liquid to properly rise in a weightless
environment of 0.43/14.696=about 3% or about 0.38 inches, which
subtracts 0.0136 pounds from the 0.43 pounds per square inch
increase or an error rate of about 3.16%.
[0070] When trying to measure for benchmarks which are 20%
different, the error rate becomes relatively larger as to each
benchmark. More accurate measurement introduces more relative error
for larger sets of smaller benchmarks. By placing the sensor at or
near the centerline of the shank 215 the ability of the error is
virtually eliminated. Further, by providing a wider fitting at the
shank 215, the level of rise in liquid to support a transmitted
rise in gas pressure will be mitigated. As seen in FIG. 5, the
conduit 237 terminates at a fitting 241 which is attached over an
upwardly extending branch 243 which forms a portion of a "T"
fitting with the shank 215.
[0071] The size of the fitting 241 creates a diameter which is
significantly greater than the cross sectional area of the conduit
237. This enables a much lesser rise in fluid within the shank 215
for a given pressure increase transmitted through the conduit 237.
The conduit 237 is preferably about one quarter inch in diameter or
smaller, to give a cross sectional area of about 0.0049 square
inches. The shank may be about 0.5 inches as well as the upwardly
extending branch 243. 0.5 inches in diameter equals about 0.78
square inches. This ratio is about 0.78/0.0049 or about 16:1. This
enables one sixteenth less fluid rise for each increase in pressure
than would be the case for a single thin vertical fluid line
extending upwardly from the shank 215. For any rise in liquid 75
displacing air in the conduit 237, there will be a proportional
reduction in error. For the dimensions given, even if a vertical
column were present (which it is not present) the error would be
reduced by a factor of 16. Any other sources of error will be
similarly reduced, and the configuration of FIG. 5 helps the
conduit 237 remain more liquid free and to clear itself when the
main reservoir 31 is dumped for cleaning.
[0072] The invention has been described with respect to a food
service indicator system which replaces a sight glass on liquid
dispenser food systems and including temperature and time functions
to enable a higher level of food service quality. However, the
techniques and structures of the invention can be applied to many
similar sets of structures where level indicators, and multiple
characteristics are to be taken to account in computing an alert
condition, and more particularly where a need to segregate sensor
and indicator function in a limited area to enable a greater
unobstructed surface of equipment.
[0073] Although the invention has been derived with reference to
particular illustrative embodiments thereof, many changes and
modifications of the invention may become apparent to those skilled
in the art without departing from the spirit and scope of the
invention. Therefore, included within the patent warranted hereon
are all such changes and modifications as may reasonably and
properly be included within the scope of this contribution to the
art.
* * * * *